IPv6 contact for www.citrix.com - MTU problem?

[Ryan Rawdon]

On Aug 18, 2011, at 12:40 AM, Kurt Jaeger wrote:

> Hi!
> 
>> Looks like www.citrix.com has MTU problems... I fail to browse the page
>> from my dualstacked home site here. Anybody else able to replicate
>> problem?
> 
> Same problem from here:
> 
> home$ traceroute6 -n www.gslb.citrix.com
> traceroute6 to www.gslb.citrix.com (2001:1890:111e:201::15) from 2001:14f8:200::1, 64 hops max, 12 byte packets
> 1  2001:14f8:200::404  0.379 ms  0.351 ms  0.367 ms
> 2  2001:14f8:3:1::3  21.371 ms  21.844 ms  21.599 ms
> 3  2a01:1e8:2:3::1  22.723 ms *  22.756 ms
> 4  2a01:1e8:1:1::8  26.581 ms  26.346 ms  26.098 ms
> 5  2001:7f8::1b1b:0:1  26.099 ms  26.588 ms  37.592 ms
> 6  2001:470:0:1d2::1  43.211 ms  38.215 ms  38.349 ms
> 7  2001:470:0:128::1  105.797 ms  112.792 ms  106.188 ms
> 8  2001:470:0:1dd::2  113.296 ms  113.051 ms  113.178 ms
> 9  * * *
> 10  * * *
> 

I don't believe that traceroute is indicative of an issue - my traceroute6 looks the same but www.citrix.com loads correctly (and I am behind a HE Ashburn tunnel at home which should invoke the PMTUD issue if I was hitting an instance afflicted by the potential PMTUD issue).  The hop that you receive the last answer from (as7018-att.10gigabitethernet2-3.core1.nyc4.he.net) appears to be the HE-AT&T network edge, so likely the ICMP6 responses for traceroute just are [unrelatedly] not making it back.

For me, if I let the traceroute continue to run, hop 12 does show up eventually even though hops 6-11 time out:

nova-dhcp-host109:~ ryan$ traceroute6  www.gslb.citrix.com
traceroute6 to www.gslb.citrix.com (2001:1890:111e:201::15) from 2001:470:8:769:223:6cff:fe88:f96e, 64 hops max, 12 byte packets
 1  tank  1.218 ms  1.042 ms  1.138 ms
 2  u13-1.tunnel.tserv13.ash1.ipv6.he.net  9.493 ms  141.957 ms  12.289 ms
 3  gige-g4-12.core1.ash1.he.net  17.274 ms  11.686 ms  7.577 ms
 4  10gigabitethernet1-2.core1.nyc4.he.net  22.412 ms  17.110 ms  12.254 ms
 5  as7018-att.10gigabitethernet2-3.core1.nyc4.he.net  15.004 ms  16.265 ms  150.646 ms
 6  * * *
 7  * * *
 8  * * *
 9  * * *
10  * * *
11  * * *
12  2001:1890:1fff:fffd::1  98.272 ms  31.802 ms  50.091 ms
13  * * *
14  * *


That said, if www.citrix.com connects but fails to load for you, then indeed you're probably seeing the same issue that Daniel is.